Apparatus for embossing moving webs

ABSTRACT

An apparatus for embossing the surface of a moving web at spaced intervals or embossing individual work pieces moving in succession past a work station and employing a heated embossing tool mounted for reciprocal motion and cooperated with a back-up roll during its work stroke to press a transfer web into contact with the work piece as it moves over the roll. The embossing tool is lifted clear of the web during the return stroke. The transfer web is advanced during the embossing operation at substantially the same rate as the moving web and retracted during the return stroke of the die at a reduced rate to effectively feed the web progressively through the apparatus and present a useable transfer surface at each work stroke.

wasted @tates atent 1191 1111 5,815,49 Bahnmiiiler .lune 11, 1974 APPARATUS FOR EMBOSSNG MOVING 2,906,203 9/1959 Grosse 101/336 WEBS 2,935,934 5/1960 Williams et a1. 101/336 X 3,304,856 2/1967 Birch 101/27 [75] Inventor: Karl Bahnmull r, D t 3,405,637 10/1968 c61w111 1,01/244 Switzerland 3,411,438 11/1968 Reader et 101/9 3,432,020 3/1969 Caudill et a1. 197/151 [73] Assign: MADAG f f 3,636,866 1/1972 Stommel et a1 101/298 x Apparatebau Dietilkon AG, Zunch, Switzerland Primary Examiner-Robert E. Pulfrey [22] Filed: Jan. 19, 1973 Assistant Examiner-Paul J. Hirsch 1 pp NO: 324,908 gfirrzlrt, 0r Fzrm-Browne, Beveridge, De-

[] Foreign Application Priority Data 57 ABSTRACT Feb. 1, 1972 Switzerland 1442/72 An apparatus for embossing the surface of a moving web at spaced intervals or embossing individual work [52] US. Cl 101/22, 101/27, 1 ()l/244 pieces moving in Succession past a work station and [51] P B41? 119/02 33/36 B413 employing a heated embossing tool mounted for recip- [58] Field of Search 197/151, 153, 162, 163, focal motion and cooperated with a back up r0" lQ LD ing its work stroke to press a transfer web into contact 297 with the work piece as it moves over the roll. The embossing tool is lifted clear of the web during the return [56] References C'ted stroke. The transfer web is advanced during the em- UNITED STATES PATENTS bossing operation at substantially the same rate as the 1,630,824 5/1927 Boehner 101/27 moving web and retracted during the return stroke of 2,309,645 2/1943 Harrington et a1. 101/297 X the die at a reduced rate to effectively feed the web 2,381,921 8/1945 Nord progressively through the apparatus and present a use- 2,621,435 12/1952 Webe able transfer surface at each work stroke. 2,693,871 11/1954 Stahl et al 2,714,268 8/1955 Battey 41/7 9 Claims, 4 Drawing Figures SHEET 3 or 4 PATENTEDJUM 1 1 I974 PATENTEDJUH 1 1 m4 APPARATUS FOR EMBOSSING MOVING WEBS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an apparatus for identification marking of moving material webs or of individual flat work pieces moving in sequence by use of an embossing foil whose print or ink application is transferred, by means of a heated embossing tool, to the web of material or to the work pieces.

2. Description of the Prior Art Machines and other devices for production of embossings by means of transfer foils, in which a moving web of goods is intermittently advanced past an embossing stamp that executes a lifting motion in at least a narrow zone, are known in various forms of embodiment. If the web of material is nevertheless to move at a uniform speed as it is delivered to and removedfrom the apparatus, it is necessary to employ a take-up or balancing device of the type disclosed, for example, in Swiss Pat. No. 407,690. Experience'has shown that machines of this kind are very limited in their output and that disturbance frequently occurs at high operating speeds.

Embossing machines are also known which employ a heated embossing tool in the form ofa driven cylinder which presents one or more embossing die sections on the periphery. If such an embossing cylinder is to be able to turn with uniform peripheral speed corresponding to the speed of the materialweb, the spacing of the successive impressions is thereby also determined. As soon as thereis the desire to be free of this limitation, which is to say, to be able to be free of the. previously mentioned spacing, major difficulties arise with respect both to the driving of the embossing tool which then, in spite of its great mass must be strongly accelerated or retarded, and with respect to the advance of the embossing foil. Here it must be observed that a variable accelerated or intermittent advance of the embossing foil is a delicate operation because a thin narrow embossing foil tears readily. It is likewise to be observed that a fully cylindrical heated embossing tool takes up a lot of space, and because of the rotation that is always in the same direction, delivery of current required to heat the embossing die can be affected only by means of sliding contacts which are subject to wear.

SUMMARY OF THE INVENTION The invention is addressed to the problem of obviating these drawbacks. According to the invention, the

problem is solved in that (a) the embossing tool, in a manner that is known per se, is constituted as a lever or arm opposite a counter pressure or back-up roll that supports the web of material or succession of work pieces, the said lever or arm being reciprocatingly swingable past the said counter pressure roll on a supporting piece, and (b) a device for imparting a controlled swinging movement to the embossing tool also includes means operable in cadence with the swinging of the embossing tool to control the distance between the supporting piece of the embossing tool and the counter pressure roll in such away'that during each swinging work stroke of the embossing tool, or during at least the major part of such a stroke, the mentioned distance is maintained so that the embossing application at a standard value is guaranteed, and during every return stroke of the embossing tool the said distance at the start of the stroke is increased above the standard value, while at the end of the stroke it is diminished again to the standard value.

It is obvious that in such a construction the size, and hence the space requirement and bulk of the embossing tool can be much reduced as compared to the full cylinder tool, whereby because of the diminished bulk and the reciprocating motion, the functional drive is much easier to effect, e.g., by means of a cam mechanism. Also delivery of current to the heating element incorporated in the embossing tool can be affected simply via flexible leads. Moreover, there are favorable conditions for a mechanism that greatly reduces the danger of tearing the embossing foil, for intermittent advance of the foil.

An advantageous embodiment of the subject of the invention is further characterized in that the supporting part on which the embossing tool is swingably supported comprises a supporting shaft eccentrically seated in an elementthat is rotatably mounted on a shaft that is fixed with reference to the axis of rotation of the counter pressure roll, and oscillated back and forth by a cam plate that executes one revolution during each work cycle of the device.

Such an arrangement offers the advantage, among others that the counter pressure .roll can be allowed to turn about a stationary shaft and the rhythmic drive of the element that supports the eccentric supporting shaft can be combined relatively simply with the swing drive mechanism of the embossing tool. I

An embodiment of the subject of the invention that presents a device for advancing the embossing foil is further characterized in that the embossing foil advance device is so combined with that for the embossing tool swing drive that during each working swing stroke of. the embossing tool the section of embossing foil that is near it is moved forward at a speed equal to the peripheral speed of the embossing tool, and with each return swing stroke of the embossing tool, the section of embossing foil near it is moved back at a speed that is less than the peripheral speed of the embossing tool.

As is to be described below, such an embodiment can be so constructed that the effective embossing foil advance per work cycle can be simply adjusted, smoothly, between a minimum value that is close to zero and a maximum that corresponds approximately to the greatest length of the embossing.

BRIEF DESCRIPTION OF THE DRAWINGS The attached drawing shows an example of an embodiment of the subject of the invention.

FIG. 1 is an elevation view of the embossing device with the means for adjusting the embossing pressure shown in section, and the movable parts being shown in the position that they assume at the start of a work cycle, and with the embossing foil advancing means being set fora very slight advance of the foil;

FIG. 2 shows a view similar to that of FIG. 1, in which however the movable parts being shown ,in the position that develops after execution of half a work cycle;

FIG. 3 is a view similar to that of FIG. I, but with the embossing foil advance set at its maximum; and

FIG. 4 shows a section of a detail along line IVIV of FIG. 1. 1

DESCRIPTION OF THE PREFERRED EMBODIMENT Numeral 1 in the drawing designates a counter pressure roll of a suitable driven work conveyor system, concerning which in the present example it is assumed that it is freely rotatable about a shaft that is stationary, among other things, with reference to a pipe 2, that serves as a bearing element, and with reference to the axis of rotation of a drive shaft 3 on which a rigid supporting frame 4 is swingably but non-slidably borne by bearing means that are not illustrated.

Letter W designates the web of material, concerning which it is assumed that it moves at uniform speed in the direction of arrow w on a rubber elastic (e.g., VULKOLLAN, registered trademark) jacket 5 of counter pressure roll 1, e.g., toward a packaging machine. The term web of material means for example a continuous web of paper, fabric, plastic or metallic foil: the term sequence of flat work pieces means a continuous succession of individual flatwork pieces, e.g., package sections, lables, etc., which temporarily may be glued to a conveyor belt or otherwise held fast. The term sequence of round parts means an intermittent succession of round work pieces, e.g., cylindrical cast pieces that halt in the embossing position and that turn on their own axes. In the following discussion, for the sake of simplicity, only a web of material is considered.

In a supporting member 7 fixed to the supporting frame 4 by bolts 6, an essentially cylindrical supporting element 8 is rotatably borne. This element 8 presents a bore that is shifted eccentrically downward by the amount e (FIG. 1). In the said bore there is seated a.

supporting shaft 9 whose terminal portions pivotally support embossing tool 10 with embossing die 10a, constituted as a two armed lever is borne so that it is reciprocatingly swingable. It is clearly to be seen that if supporting element 8 executes a counterclockwise rotation by angle a from the position illustrated in FIG. 1, for example, supporting shaft 9 and embossing tool lilalong with it will undergo a certain lifting.

Near working portion 10a of embossing tool 10 there are electrical heating elements (not shown) and an appurtenant thermostatic switch. The connection to a current supply is effected by flexible leads The swing drive mechanism for embossing tool 10 presents a cam plate 11 fixed on drive shaft 3, the profile of said plate being contacted by a cam follower 12. Said roll is borne on a touch lever 14 that is loaded by a tension spring 13. Said lever 14 is borne on a fixed bearing pin 15 on supporting frame 4 and connected by an arm 16 with the upper arm of the lever that constitutes the embossing tool.

The mechanism for the reciprocation motion of element 8 by the mentioned angle a (said element 8 supporting the eccentric embossing tool shaft 9) presents, in addition to cam plate 11, a fixed cam 17 on shaft 3, whose profile is contacted by a cam follower 18 that is borne on a'touch lever 19. The said lever 19 is borne on a bearing pin 15, and as in the case of lever 14, it is spring loaded and connected to element 8 by an arm Numeral 21 designates the embossing foil or transfer tape whose print or color application is transmitted by means of embossing tool 10a onto material web W. A device now to be described, for the advance of this embossing foil, is so combined with the above described device ll, 12, i3, 14, 16 for the swing drive of the embossing tool that during each working swing stroke of the embossing tool, the embossing foil section near it is advanced in the direction of movement of web W at the same speed as the peripheral speed of the embossing work tool, and with each return swing stroke of the embossing tool the section of embossing foil near it is moved back at a speed that is less than the peripheral speed of the embossing tool. From this difference of forward and backward speed, there is obtained the effective advance of the embossing foil strip per work cycle. The embossing foil advance device includes a supply reel 22, a wind up reel 23, and an articulated fourbar control linkage for supporting and guiding a bight of the embossing foil along a path extending adjacent to the web at the work station. The four-bar linkage and its associated foil guides include control levers 24, 25 borne at points 26 and 27 respectively on support frame 4, deflector rolls 28, 29, borne on control lever 24 near its bearing position or at its lower extremity, deflector rolls 30, 31 borne on control lever 25 at its bearing position or at its lower end, an arm 32 that connects an upper arm of control lever 24 with an articulated pin 33 fixed on the embossing tool 10, and that is of such length that lever 24 remains generally parallel to embossing tool 10. in addition there is an arm 34 interconnecting control levers 24, 25, one end of which arm is articulated at 35 to control lever 25, the other end being articulated at 36 to slide 37. The said slide 37 is adjustable in a slanting groove 38-of lever 24, and fixabie in the groove by tightening of a clamp 39. As described below in detail, the setting of slide 37 on control lever 24. effects a change of the swing stroke of control lever 25. This in turn effects, in cooperation with the drive mechanism for wind up reel 23, a change of the advance of the embossing foil per work cycle of the device. I 2

Supply reel 22 is braked in a known way on a supporting shaft 40 fixed in the support frame 4.

For acceptance and locking in of the wind up reel, there is provided according to H6. 4, a hub 4l on which there are two jaws 41a borne on two shafts 42 that are adjacentto each other, which jaws after setting of the wind up reel 23 can be brought to intimate friction locking application on reel 23 by the turning of a spreader pin 43. Hub 4! is held by a nut 44 and a spring 45 in axial direction on a shaft 46, am: connected therewith by a wedge 47. Shaft 46 is rotatably borne by two ball bearings 48 in a bearing element 4a of supporting frame 4 and connected by a wedge 49 with the inner ring 50 of a return lock whose outer ring 51 is fixed by a screw pin 53 on bearing element 4a. Rollers 52 act in the usual way between rings 50, 51 to prevent a backward rotation counterclockwise as seen in F108. l-3 of shaft 46 and reel 23. Shaft 46 has a flat head 46a at its forward end, against which head a friction plate 54 bears. A crank ring plate 55 is disposed between the latter and a base plate 56 bearing on the inner race of adjacent ball bearing 48, itself freely rotatable on shaft 46 but pressed by the force of spring 45 against friction plate 54. Therewith crank ring plate 55 is connected by a kind of friction coupling or friction clutch with shaft 46. In an eccentric bore hole of crank ring plate 55 there is an articulation pin 57 by means of which one end of an arm 58 is articulated to crank ring plate 55,

while the other end of this couple 58 is articulated on the upper end portion of touch lever 14.

The mechanism described primarily with reference to FIG. 4 acts, within each work cycle of the device during the work swing stroke (from left to right in FIGS. 1-3) of the embossing tool 10, of control lever 24, and depending upon the setting of slide 37 of control lever 25 also to wind up a length of embossing foil strip 21 on wind up reel 23, said length of foil strip being determined by the lag of control lever 25 with reference to lever 24, and the lag of deflector roll 31 with reference to deflector roll 29, winding off the foil from supply reel 22. The crank ring plate 55 driven by touch lever 14 of course always travels the same path of rotation: a locking of shaft 46 via the friction clutch to which friction plate 54 belongs can occur only to the extent necessary for the winding up of the length of embossing foil strip 21, however, Moreover, it must be rememberedhere that a reverse rotation of shaft 46 and wind up reel 23, hence an unwinding of the embossing foil strip from these elements, is made impossible by reverse lock 50, 51, 52. In the backward swing stroke of embossing tool 10 and of touch lever 14, (by

means of couple 58) only crank ring plate 55 is reversed.

The embossing pressure acting during the embossing process between effective section 10a of embossing tool 10, embossing foil strip, material web W and jacket 5 of counter pressure roll 1 is adjustable because of the device shown at the left in FIGS. I and 2 where it is to be recalled that the supporting frame 4 is swingably borne on drive shaft 3. A projecting bolt 59 is welded fast on stay pipe 2. It presents a nut 60 that can be secured by a counter nut 61. An eye 4b of supporting frame 4 is applied to said nut 60. During the actual embossing process, through the reflex action of the embossing pressure, there is a tendency to slight forward swinging on the part of supporting frame 4. This tendency is counteracted by a series of plate springs 62 that are disposed between a cap 63 bearing on eye 4b and a nut 64 that is adjustable on bolt 59 and securable by counter nut 65.

For description of the functioning of the apparatus as a whole, the positions according to FIGS. 1 and 3 are taken as starting position, whereby in FIG. I slide 37 is set to produce a minimal embossing foilstrip advance (assuming a low embossing image measured in the direction of advance) whereas in FIG. 3 slide 37 is set to produce a maximum advance of the embossing foil strip.

For the whole work cycle it is assumed that drive shaft 3 rotates at constant velocity.

During the first half turn of drive shaft 3 from the position of FIG. 1 the effective swing or work stroke of embossing tool 10 occurs because of the spiral rise of the contacted profile section of cam plate 11, with lowered supporting shaft 9. The second half turn has three stages, the first of about 30, the second of about 120, and the third of about 30. In the first, embossing tool 10 is lifted into its right-hand reverse position by the rising portion of cam plate 17, hence by rotation of supporting element 8 by angle a. In the second stage, from the-descending portion of the profile of cam plate 11, there is a backward swing or return stroke of the lifted embossing tool 10. In the third stage, there is a descent of embossing tool 10 which is in the left-hand reverse position (or starting position). It is clear that the actual embossing process takes place only during the middle part of the effective swing stroke, whereby the angle that the embossing tool then describes depends upon the actual length, measured peripherally, of the effective part 10a of embossing tool 10. I

It is also clear that the constant peripheral speed of this part 10a, in the reverse of the effective swing or work stroke, must be set with utmost precision with reference to the constant rate of advance of material web W. Taking into account the steepness of the spiral portion of cam plate 11 that controls the effective swing stroke, the rotational velocity is also given at which drive shaft 3 must be driven at least during the first half of the work cycle.

Also, the section of the embossing foil strip 21 passing from deflector roll 29 to deflector roll 31 must be advanced during this first half of the work cycle at a speed (from left to right) that is at least substantially equal to the peripheral speed of embossing tool part 10a; at the start of the embossing process (during which the equalizing is more or less total) there is synchronized running. Only in this way can there be a perfect embossing, and prevention of an undesired tearing action exerted on embossing foil strip 21. This'equalizing is effected in that (a) the length of arm 32 is equal to the distance between shafts 9 and 26 of embossing tool 10 and of control lever 24 respectively when em-- bossing tool 10 is lowered (i.e., supporting element 8 not turned by angle a (b) the effective radius of'embossing tool 10 is equal to the distance of the horizontal embossing foil strip portion from shaft 26 of control lever 24. I

In spite of the mentioned synchronizing, an embossing foil strip advance is produced during an entire work cycle, asfollows:

In the setting of slide 37 on control lever-24' according to FIGS. 1 and 2, forminimum advance, the articulating shaft 36 of arm 34 is so applied to control lever 24, as compared to articulation point 35 of this arm 34 on control lever 25, that during the effective swing from the position of FIG. 1 into that of FIG. 2 the control lever 25 lags only slightly behind control lever 24. As illustrated in FIG. 2, deflector roll 29 runs through path 0, while deflector roll 31 on the contrary passes over the somewhat shorter path d. The difference c d is equal to the advance of the embossing foil strip because during the effective swing of parts 10, 24, 25 the wind up reel 23 is driven by means of touch lever 14, arm 58 and the mechanism described with reference to FIG. 4. This consequently winds the strip length 0 d that is passing on deflector roll 31, and web position Al moves at the winding reel toward A2 (FIG. 2). In the reverse swing the same strip length might wind off again from wind up reel 23: this is prevented by reverse lock 50-52 (whereby nonetheless crank ring plate is moved back by arm 58). Thus the same strip length must wind off from supply reel 22 in the backward swing of parts 10, 24, 25; strip position Bl thus moves toward B2.

In the setting of slide 37 on control lever 24 according to FIG. 3, for maximum embossing foil strip advance, the process is analogous, but with the principal difference that now the articulation point 36 in the reciprocating swing of parts 10, 24 moves along an arc whose end points are approximately the same distance on either side of the straight connecting line between bearing point 26 and articulation point 35 of couple 34 on control lever 25. Consequently only arm 34 is reciprocatingly moved about articulation point 35 whereas control lever 25 is practically stationary. While path c traversed by deflector roll 29 remains unchanged, path a traversed by deflector roll 31 is now practically zero. The path of advance thus in this case amounts to c o c: in the forward swing stroke, strip position Al passing by wind up reel 23 moves toward A2 and during the reverse swing stroke the strip position Bl at the supply reel moves toward B2.

The magnitude of the strip advanced corresponding to path c is adjusted in a way that corresponds to the height of the embossed image to be produced (still higher as in the illustrated length of work part a of embossing tool 10 as in FIG. 3). It is obvious that between the two extreme values of the advance path, any arbitrary intermediate value can be set by suitable adjustment of slide 37 on control lever 24. For indication of the resulting advance, a scale can be provided on one of these two parts and an index on the other. Similarly it is clear that, in a way not illustrated, the effective part of the embossing stamp can be exchangeably fixed to the body of said stamp.

The, distance measured from middle to middle of two successive embossings amounts to about (10 for the forward swing stroke 1c for the reverse swing stroke) with rpm of the drive shaft 3 continuously adjusted to the speed of the material web. This distance can be shortened (to a value between 1c and 20) if it is provided that angle b on cam plate 11 which governs the backward swing be made as small as possible. The backward swing, as already noted, occurs from the spiral during the turning of cam plate 11 by an angle that amounts to approximately 360 b. The larger this angle (360 b) with respect to b, the shorter the distance of two successive embossings. However, it can be enlarged arbitrarily beyond the value 20 if the drive of shaft 3 between two successive rotations is stopped for a longer or shorter interval. Thereby shaft 3 can-be driven by a single-revolution coupling of known construction, whereby the switching on of such a coupling can be controlled by known means, e.g., presenting a photocell that responds to marking points on the material web (or on any work piece fixed on a conveyor belt).-.

There are various possible modifications of the described example of embodiment. Touch lever 19 for example, via an angle lever, could vertically displace shiftable positions of counter pressure roll 1, up and down, to produce an effect similar to that produced in the described example by raising and lowering support shaft 9.

I claim:

1. In an apparatus for marking a moving workpiece by pressing a transfer tape having a coating of marking material thereon into engagement with the moving workpiece, said apparatus including driven conveyor means for conveying the workpiece past a work station, an embossing die carried by an arm mounted for pivotal oscillatory movement about an axis extending transverse to and spaced from the path of movement of the workpiece at the work station, tape feed means for advancing the transfer tape through said apparatus, and drive means for driving the embossing die support arm in its oscillatory movement and for shifting the pivotal mounting of the arm toward and away from the work station in synchronization with its oscillatory movement to drive the embossing die along a closed path including a work stroke portion in which the die moves at the same rate and tangential to the workpiece with the transfer tape pressed therebetween and a return stroke portion spaced from and in a generally opposite direction to the work stroke, the improvement wherein said tape feed means comprises an articulated four-bar linkage including first and second elongated bars each having one end pivotally supported on a common ground and extending in spaced relation in the same general direction, a third bar extending between and having its opposed end portions pivotally connected to said first and second bars, a braked tape supply reel and a driven take-up reel, guide means on said first and second bars at points spaced from their respective pivotal supports for guiding the tape between said supply and take-up reels with a length of the tape extending between the guide means on said first and second bars and generally tangential to the path of said embossing die during said work stroke, drive means oscillating said first and second bars about their respective pivotal supports in synchronization with said embossing die to move said length of tape in the same direction and at the same speed as said embossing die during at least a portion of said work stroke, said third bar being pivot ally connected to said first and second bars at points spaced unequal distances from their respective pivotal supports to produce a shorter movement of the guide means closest said take-up reel to thereby shorten said length of tape during its movement parallel to said die during said work stroke, and friction clutch drive means driving said take-up reel to take up a length of tape equal to the amount said length is shortened on each said work stroke.

2. The apparatus as defined in claim 1 further comprising reverse locking means preventing reverse movement of said take-up reel whereby the return movement of said first and second bars following said work stroke lengthens said length of tape between said guide means, thereby drawing a length of tape from said supply reel equal to the length wound onto said take-up reel during the preceding work stroke.

3. The apparatus as defined in claim 2 further comprising means for adjusting the point at which said third bar is connected to at least one of said first or second bars to thereby adjust the difference in travel of said guide means on said first and second bars during their oscillatory movement.

4. The apparatus as defined in claim 1 wherein the length of one of said first or second bars from its pivotal support to said tape guide means is substantially equal to the length of said embossing die supporting arm from its pivotal support to said embossing die, said one bar and said arm extending in generally parallel spaced relation throughout their respective oscillatory movements.

5. The apparatus as defined in claim 4 wherein said means driving said arm in its oscillatory movement includes means maintaining the distance between its pivotal support and said work station constant during at least a substantial portion of said work stroke to thereby apply a substantially uniform pressure to the transfer tape by said embossing die during said portion of said work stroke.

6. The apparatus as defined in claim 5 wherein the pivotal support for said arm comprises a shaft mounted for rotation about an axis extending transverse to and spaced from the path of the workpiece, and an eccentric bearing on said shaft supporting said arm member, and cam actuating crank means for oscillating said shaft about its axis to shift said axis toward and away from said work station in synchronization with the oscillatory movement of said arm.

7. In an apparatus for marking a moving workpiece by pressing a transfer tape having a coating of marking material thereon into engagement with the moving workpiece, tape feed means comprises an articulated four-bar linkage including first and second elongated bars each having one end pivotally supported on a common ground and extending in spaced relation in the same general direction, a third bar extending between and having its opposed end portions pivotally connected to said first and second bars, a braked tape supply reel and a driven take-up reel, guide means on said first and second bars at points spaced from their respective pivotal supports for guiding the tape between said supply and take-up reels with a length of the tape extending between the guide means on said first and second bars and generally tangential to the path of said moving workpiece, drive means oscillating said first and second bars about their respective pivotal supports to move said length of tape in a closed path including a marking portion extending the same direction and at the same speed as said workpiece whereby the tape can be pressed into contact with said workpiece with an embossing die during said marking portion of said closed path, said third bar being pivotally connected to said first and second bars at points spaced unequal distances from their respective pivotal supports to produce a shorter movement of the guide means closest said take-up reel and thereby shorten said length of tape during its movement parallel to said die during said work stroke, and friction clutch drive means driving said take-up reel to take up a length of tape equal to the amount said length is shortened on each said work stroke.

8. The apparatus as defined in claim 7 further comprising reverse locking means preventing reverse movement of said take-up reel whereby the return movement of said first and second bars following said work stroke lengthens said length of tape between said guide means, thereby drawing a length of tape from said sup ply reel equal to the length wound onto said take-up reel during the preceding work stroke.

9. The apparatus as defined in claim 8 further comprising means for adjusting the point at which said third bar is connected to at least one of said first or second bars to thereby adjust the difference in travel of said guide means on said first and second bars during their oscillatory movement. 

1. In an apparatus for marking a moving workpiece by pressing a transfer tape having a coating of marking material thereon into engagement with the moving workpiece, said apparatus including driven conveyor means for conveying the workpiece past a work station, an embossing die carried by an arm mounted for pivotal oscillatory movement about an axis extending transverse to and spaced from the path of movement of the workpiece at the work station, tape feed means for advancing the transfer tape through said apparatus, and drive means for driving the embossing die support arm in its oscillatory movement and for shifting the pivotal mounting of the arm toward and away from the work station in synchronization with its oscillatory movement to drive the embossing die along a closed path including a work stroke portion in which the die moves at the same rate and tangential to the workpiece with the transfer tape pressed therebetween and a return stroke portion spaced from and in a generally opposite direction to the work stroke, the improvement wherein said tape feed means comprises an articulated four-bar linkage including first and second elongated bars each having one end pivotally supported on a common ground and extending in spaced relation in the same general direction, a third bar extending between and having its opposed end portions pivotally connected to said first and second bars, a braked tape supply reel and a driven take-up reel, guide means on said first and second bars at points spaced from their respective pivotal supports for guiding the tape between said supply and take-up reels with a length of the tape extending between the guide means on said first and second bars and generally tangential to the path of said embossing die during said work stroke, drive means oscillating said first and second bars about their respective pivotal supports in synchronization with said embossing die to move said length of tape in the same direction and at the same speed as said embossing die during at least a portion of said work stroke, said third bar being pivotally connected to said first and second bars at points spaced unequal distances from their respective pivotal supports to produce a shorter movement of the guide means closest said take-up reel to thereby shorten said length of tape during its movement parallel to said die during said work stroke, and friction clutch drive means driving said take-up reel to take up a length of tape equal to the amount said length is shortened on each said work stroke.
 2. The apparatus as defined in claim 1 further comprising reverse locking means preventing reverse movement of said take-up reel whereby the return moVement of said first and second bars following said work stroke lengthens said length of tape between said guide means, thereby drawing a length of tape from said supply reel equal to the length wound onto said take-up reel during the preceding work stroke.
 3. The apparatus as defined in claim 2 further comprising means for adjusting the point at which said third bar is connected to at least one of said first or second bars to thereby adjust the difference in travel of said guide means on said first and second bars during their oscillatory movement.
 4. The apparatus as defined in claim 1 wherein the length of one of said first or second bars from its pivotal support to said tape guide means is substantially equal to the length of said embossing die supporting arm from its pivotal support to said embossing die, said one bar and said arm extending in generally parallel spaced relation throughout their respective oscillatory movements.
 5. The apparatus as defined in claim 4 wherein said means driving said arm in its oscillatory movement includes means maintaining the distance between its pivotal support and said work station constant during at least a substantial portion of said work stroke to thereby apply a substantially uniform pressure to the transfer tape by said embossing die during said portion of said work stroke.
 6. The apparatus as defined in claim 5 wherein the pivotal support for said arm comprises a shaft mounted for rotation about an axis extending transverse to and spaced from the path of the workpiece, and an eccentric bearing on said shaft supporting said arm member, and cam actuating crank means for oscillating said shaft about its axis to shift said axis toward and away from said work station in synchronization with the oscillatory movement of said arm.
 7. In an apparatus for marking a moving workpiece by pressing a transfer tape having a coating of marking material thereon into engagement with the moving workpiece, tape feed means comprises an articulated four-bar linkage including first and second elongated bars each having one end pivotally supported on a common ground and extending in spaced relation in the same general direction, a third bar extending between and having its opposed end portions pivotally connected to said first and second bars, a braked tape supply reel and a driven take-up reel, guide means on said first and second bars at points spaced from their respective pivotal supports for guiding the tape between said supply and take-up reels with a length of the tape extending between the guide means on said first and second bars and generally tangential to the path of said moving workpiece, drive means oscillating said first and second bars about their respective pivotal supports to move said length of tape in a closed path including a marking portion extending the same direction and at the same speed as said workpiece whereby the tape can be pressed into contact with said workpiece with an embossing die during said marking portion of said closed path, said third bar being pivotally connected to said first and second bars at points spaced unequal distances from their respective pivotal supports to produce a shorter movement of the guide means closest said take-up reel and thereby shorten said length of tape during its movement parallel to said die during said work stroke, and friction clutch drive means driving said take-up reel to take up a length of tape equal to the amount said length is shortened on each said work stroke.
 8. The apparatus as defined in claim 7 further comprising reverse locking means preventing reverse movement of said take-up reel whereby the return movement of said first and second bars following said work stroke lengthens said length of tape between said guide means, thereby drawing a length of tape from said supply reel equal to the length wound onto said take-up reel during the preceding work stroke.
 9. The apparatus as defined in claim 8 further comprising means for adjusting the point at which saId third bar is connected to at least one of said first or second bars to thereby adjust the difference in travel of said guide means on said first and second bars during their oscillatory movement. 